Coordinated MIMO (Co-MIMO) is a key physical-layer technology of the IMT-Advanced standard. In a cellular system that multiplexes frequency globally, inter-cell interference is a main factor of restricting mobile communication performance. The conception of Co-MIMO is to coordinate signal transmission between multiple Base Stations (BS) so as to relieve interference between cells. In a Co-MIMO system, multiple BSs coordinate to provide communication services for multiple Mobile Stations (MS) simultaneously.
Unlike the traditional Space Division Multiple Access (SDMA) precoding scheme with finite feedback of Channel State Information at the Transmitter (CSIT) of a single BS, the Co-MIMO system is inherently characterized by: Each channel from a coordinating BS to an MS has different quality. Consequently, the signal received by the MS from each of different BSs has a different average Signal-to-Noise Ratio (SNR). For the purpose of precoding design based on the channel state, the MS needs to feedback channel state information of the channel to the BS. In the prior art, the channel information feedback bits are allocated averagely regardless of the channel quality. As a result, the channel of high quality and the channel of low quality have the same number of channel information feedback bits.
In the prior art, the channel information feedback bits are allocated averagely, the amount of channel state information fed back is limited, and the feedback gain is low.